Engine coupler



y 1967 D. w. SHOEMAKER ETAL 3,328,976

ENGINE COUPLER Filed on. 22, 1965 INVENTORS David W. Shoemaker BY James D. Shoemaker THEIR ATTORNEYS Park, Pa.

United States Patent 3,328,976 ENGINE COUPLER David W. Shoemaker, RD. 2, Ford City, Pa. 16226. and'James D. Shoemaker, 3235 Sylvan Road, Bethel 15102 lFiled Oct. 22, 1965, Ser. No. 500,592 9 Claims. (Cl. 64-1) Our invention relates to a coupler arrangement for connecting the crankshafts of two internal combustion engines and more particularly to a frame to which the engines are attached for accurate alignment of the crankshafts and a rigid coupler for rigidly connecting the aligned crankshafts so that two low cost mass produced engines will function as a single engine.

Numerous advantages are obtained by connecting two independent engines to function as a single unit. For example, a single engine capable of developing equivalent power is considerably more expensive than two smaller engines. Additionally, the smaller engines are less complex mechanically than a single large engine and, therefore, the maintenance of the assembly is less than with a single large engine.

It is well known to mount two engines in juxtaposition to one another and to transmit power from each engine to an axle by separate power transmission means such as belts, gears or chains. However, when two engines are independently connected to an axle, it has been found that they will slip or lag until both engines are running in phase and this will occur even though the engines are originally connected to the axle with the throws of their respective crankshafts 180 apart. The disadvantage of having the engines operating in phase is, of course, that the engines are only delivering a power thrust once in every complete revolution of the crankshaft; whereas if the engine crankshafts can bemaintained in the 180 relationship; a power thrust is obtained every half revolution. For this reason, arrangements have been proposed wherein adjacent engines have their crankshafts directly interlocked or a single one-piece crankshaft is used for both engines. The use of a one-piece crankshaft is impractical because the crankshaft must have a larger crosssectional area so that it will stand up under the torque created by the engine; and when a crankshaft is of sufficiently heavy construction to stand up under the torque created by twoengines and of suflicient length to extend through both engines, the torsional vibration at the ends of the crankshaft is excessive and a loss in power inherently results. A direct interlock between the crankshafts of two juxtaposed engines is also impractical since it is impossible to construct the mating surfaces of the shafts with sufiicient accuracy t-oeliminate all play between the shafts and, hence, the shafts twist 01f. Both end splines and longitudinal splines have been used for directly interlocking crankshafts without success.

In an attempt to overcome the problems encountered with a single crankshaft and direct interlocked crankshafts, flexible connectors have been used to interconnect the separate crankshafts of two independent engines. However, when flexible connectors are used, there is considerable twist inherent in the connector and large power loss results.

Our invention overcomes the above disadvantages by providing a completely rigid coupling between two accurately aligned juxtaposed engines to positively interconbracket 6 attached thereto,

3,328,976 Patented July 4, 1967 meet the independent crankshafts of each engine. Additionally, the use of our coupling arrangement makes it possible to take power from between the two engines rather from an end of the crankshaft as when a single crankshaft is used; and, therefore, there is no loss of power due to torsional vibration of the end of the crankshafts. Furthermore, our coupling arrangement makes it possible to utilize conventional mass produced two or four-cycle engines with no modification whatsoever to the engines thus providing a relatively large amount of power at a relatively low cost.

In the accompanying drawings, we have shown a preferred embodiment of our invention in which:

FIGURE 1 is a plan view of two connected engines;

FIGURE 2 is an end view of the coupler housing;

FIGURE 3 is a view of the coupler and crankshaft ends with the various parts separated for simplicity;

FIGURE 4 is a partial section along the longitudinal axis of the coupler; and

FIGURE 5 is a section taken on line V-V of FIG. 4.

Referring to FIG. 1 of the drawings, our apparatus includes a coupler housing or frame 1 to which each of the engines A and B is bolted by bolts 2 extending through bolt holes 3 in the housing into internal threads formed in the engine casings. The coupler housing is constructed from a pair of opposed end members 4 and rear and forward members 5. Although the housing is shown as made from four separate members, it is obvious that it may be cast as a single unit without departing from the scope of our invention. Each of the end members is shown with four bolt holes 3 located in the corners of each end member and a .center hole 7, but the number and location of the bolt holes vary depending upon the number and location of the internally threaded sockets in the engines. The bolt holes and the center hole of each end member must be accurately aligned with the corresponding holes in the opposed end member in order that the engine crankshafts C are accurately aligned when the engines are mounted on the housing; and for this reason, the holes are line bored after the housing is made. The bearing housings of the engines extend through the center holes in the end members, and the crankshafts are located in the coupler housing with their ends spaced a suflicient distance to accommodate the coupler 10. The outer surfaces of the end members 4 are parallel faced after the housing is made so that when the engines are bolted to the housing the crankshafts will be accurately aligned. The accurate manufacture of the housing insures a firm, vibration-free contact between the housing and the engines and insures that the crankshafts are accurately aligned so that there is no play between the crankshafts and the coupler shaft.

The lower edge of each end member 4 has a mounting and the horizontal flange of of bolt holes extending therethrough for mounting the coupler housing and attached engines to a vehicle frame or other support member. The mounting brackets may also be cast with the housing as a unit if desired.

As pointed out heretofore, the coupler 10 is located between the two engines within the coupler housing. The coupler consists of a coupler shaft 11 machined from a single bar and including a double sprocket 12 at its center. Each end of the shaft has a recess 13 formed therein as by drilling, and the peripheral wall of each recess has a longitudinal keyway 14 and a longitudinal crimping slot the bracket has a plurality 15 cut therein. The keyways 14 are shown 180 out of phase in FIG. 3 since it is assumed that the coupler will be used with a pair of conventional two-cycle engines and that the power strokes of the crankshafts will be 180 out of phase. Although the double sprocket 12 is shown on the coupler shaft, it is to be understood that other power takeoff means, for example, a drive gear, a timing belt gear or a belt sheave may also be used to transmit power from the coupler shaft.

As shown in FIG. 4, a key 9 is carried at the end of each engine crankshaft C, and the coupler shaft is placed onto the crankshafts so that the keys 9 extend into the keyways 14 and the crankshaft ends extend into the recesses formed in the ends of the coupler shaft. Each end of the coupler shaft is tightly clamped to a crankshaft by means of a tapered cone 16 which fits over the end of the shaft and which is squeezed about the coupler shaft throughout the periphery of the coupler shaft by a tapered nut 17 which is forced onto the tapered cone by a push nut 18. The degree of taper on the exterior of cone 16 and the interior of nut 17 is of the same angle so that force is transmitted throughout the mating surfaces of the cone and nut, and the tapered cone 16 has a longitudinal crimp slot 19 out throughout its length so that it can be compressed by the tapered nut 17. When the push nut 18 is tightened on the exterior threads 20 of the cone, the nut exerts a longitudinal force on the nut 17, and the nut squeezes the cone thereby exerting an inward normal force on the coupler shaft surface to squeeze the shaft against the corresponding crankshaft.

The keys 9 are used only to align the coupler shaft on the crankshafts so that the engine power strokes will be 180 outof phase and all force is transmitted between the coupler shaft and the engine crankshafts by the tight squeeze fit between the coupler shaft and the crankshafts. The squeeze fit is created throughout the total surface of the crankshafts located within the recesses as a result of the crimp slot 15 which is cut in the wall of each recess. As a result of the squeeze fit throughout the surface of the crankshaft ends, there is no play between the crankshafts and the coupler shaft.

Our invention has a number of important features which includes the rigid connection of a pair of conventional engines with a minimum number of parts. Additionally, our coupling arrangement provides a mounting frame for carrying the engines and accurately aligning the crankshafts; and since both engines are mounted on the same independent frame rather than being separately mounted directly on the vehicle, vibration is minimized Furthermore, our coupling arrangement is designed to permit the power takeoff means to be mounted between the engines thereby eliminating torsional vibration of the crankshaft ends. The rigidity of the coupler shaft and connection between the shaft and the crankshafts eliminates all play between the crankshafts and coupler shaft and insures that the engines will maintain the relationship in which they are originally set and, hence, no power is lost due to one engine slipping or lagging with respect to the other.

While we have shown and described a preferred embodiment of our invention, it may be otherwise embodied within the scope of the appended claims.

We claim:

1. Apparatus for rigidly coupling the crankshafts of a pair of spaced apart engines to permit said engines to function as a single unit comprising:

(A) a housing having a pair of parallel spaced end walls for supporting engines, each of said end walls being formed with a substantially centrally located opening for receiving the crankshaft of an engine supported on said end walls and said openings being aligned whereby the ends of the crankshafts extend into said housing; and

(B) a coupler located within said housing for receiving the ends of the crankshafts to rigidly connect the crankshafts, said coupler including: I

(1) an elongated coupler shaft having a coaxially located elongated recess formed in each end for receiving the end of a crankshaft and (2) a means at each recessed portion of said coupler shaft to squeeze the longitudinal wall of each recess toward the axis of said coupler shaft throughout the circumference of the recessed portion of said coupler shaft whereby a tight fit may be effected between the interior of the longitudinal wall of each recess and the circumference of a crankshaft end located in the recess.

2. Apparatus as set forth in claim 1 wherein said means for squeezing the longitudinal wall of each recess comprises:

(A) a first annular member surrounding the longitudinal wall of the recess throughout its length, a portion of the exterior surface of said annular member being tapered and a portion of the exterior surface adjacent the smaller end of said tapered portion being threaded,

(B) a second annular member having its interior formed with a taper corresponding to the taper of the exterior surface of said first annular member surrounding the tapered portion of said first annular member and having an end adjacent the threaded portion of said first annular member, and

(C) a nut threaded onto the exterior threads of said first annular member and abutting said end of said second annular member to move said second annular member relative to said first annular member.

3. Apparatus as set forth in claim 2 wherein the longitudinal wall of each recess has a slot formed therein throughout its length and the first annular member has a slot formed throughout its length.

4. Apparatus as set forth in claim 1 wherein said coupler shaft is provided on its exterior with means for driving a power takeoff member.

5. Apparatus as set forth in claim 1 wherein the interior surface of the longitudinal wall of each recess is formed with a longitudinally extending keyway adapted to receive a key carried by the end of a crankshaft located in the recess.

6. The combination of (A) a rigid engine mounting housing having a pair of parallel spaced end walls, said end walls having substantially centrally located aligned openings located therein;

(B) a coupler within said housing for rigidly connecting said crankshafts, said coupler including (1) a coupler shaft having a coaxially located elongated recess formed in each end, and

(2) a means surrounding each recessed end of said shaft to apply radially inward force to the exterior surface of the longitudinal wall of said recess to move said longitudinal wall toward the axis of said shaft; and

(C) a pair of engines, each of said engines having a crankshaft with a key located adjacent its end,

one of said pair of engines supported on the exterior of each of said end walls with its crankshaft extending through the opening in said end wall into said housing and into one of said recesses in said coupler shaft, whereby the interior longitudinal surface of each recess is squeezed tightly against the circumference of the portion of said crankshaft located within the recess by one of said means to rigidly connect said crankshafts and said coupler shaft.

7. Apparatus as set forth in claim 6 wherein said coupler shaft includes means for driving a power takeoff member.

8. Apparatus a set forth in claim 6 including a slot formed in the longitudinal Wall of each of said recesses.

9. Apparatus as set forth in claim 6 including a longitudinal keyway formed in the interior surface of the longitudinal wall of each of said recesses, the keyway in one of said recesses being angularly spaced by 180 relative to the keyway in the other of said recesses whereby the keys carried on the crankshafts fit into said keyways when the crankshaft ends are fitted into the recesses formed in the coupler shaft.

References Cited UNITED STATES PATENTS FRED c. MATTERN, 1a., Primary Examiner. 10 H. C. COE, Assistant Examiner. 

1. APPARATUS FOR RIGIDLY COUPLING THE CRANKSHAFTS OF A PAIR OF SPACED APART ENGINES TO PERMIT SAID ENGINES TO FUNCTION AS A SINGLE UNIT COMPRISING: (A) A HOUSING HAVING A PAIR OF PARALLEL SPACED END WALLS FOR SUPPORTING ENGINES, EACH OF SAID END WALLS BEING FORMED WITH A SUBSTANTIALLY CENTRALLY LOCATED OPENING FOR RECEIVING THE CRANKSHAFT OF AN ENGINE SUPPORTED ON SAID END WALLS AND SAID OPENINGS BEING ALIGNED WHEREBY THE ENDS OF THE CRANKSHAFTS EXTEND INTO SAID HOUSING; AND (B) A COUPLER LOCATED WITHIN SAID HOUSING FOR RECEIVING THE ENDS OF THE CRANKSHAFTS TO RIGIDLY CONNECT THE CRANKSHAFTS, SAID COUPLER INCLUDING: (1) AN ELONGATED COUPLER SHAFT HAVING A COAXIALLY LOCATED ELONGATED RECESS FORMED IN EACH END FOR RECEIVING THE END OF A CRANKSHAFT AND (2) A MEANS AT EACH RECESSED PORTION OF SAID COUPLER SHAFT TO SQUEEZE THE LONGITUDINAL WALL OF EACH RECESS TOWARD THE AXIS OF SAID COUPLER SHAFT THROUGHOUT THE CIRCUMFERENCE OF THE RECESSED PORTION OF SAID COUPLER SHAFT WHEREBY A TIGHT FIT MAY BE EFFECTED BETWEEN THE INTERIOR OF THE LONGITUDINAL WALL OF EACH RECESS AND THE CIRCUMFERENCE OF A CRANKSHAFT END LOCATED IN THE RECESS. 